best_practices.md

Best Practices

This is a living document where I list best practices that I discovered while working with this library. These will be integrated into the documentation someday.

General

• keep aggregates small (as few events as possible)
  • to keep their event stream small
• do validation within the aggregates before raising an event, not within the event applier
  • better performance when re-building the aggregate
  • event appliers are not responsible for validation, they just apply "facts"
• do not raise unnecessary aggregate events that don't change the state of the aggregate

Projections

• keep projections performant
  • run costly computations in a finalize method after applying a projection job to a projection
  • generally, don't call long-running functions that require a context.Context within event appliers.